References of "Souberbielle, Jean-Claude"
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See detailSupplementation with 80,000 IU vitamin D3/month between November and April corrects vitamin D insufficiency without overdosing: Effect on serum 25-hydroxyvitamin D serum concentrations.
Tournier, Herve; Tran, Nicole; Dray, Nathalie et al

in Presse medicale (Paris, France : 1983) (in press)

INTRODUCTION: Vitamin D insufficiency, defined by a 25-hydroxyvitamin D (25OHD) serum concentration<20ng/mL, is highly frequent in the French general population, especially between November and April. The ... [more ▼]

INTRODUCTION: Vitamin D insufficiency, defined by a 25-hydroxyvitamin D (25OHD) serum concentration<20ng/mL, is highly frequent in the French general population, especially between November and April. The aim of this study was to evaluate whether 80,000 IU vitamin D3 every month during this period of the year was able to maintain a 25OHD level between 20 and 60ng/mL in apparently healthy subjects whatever their basal vitamin D status. METHODS: Ninety-eight subjects volunteered to receive an 80,000 IU vitamin D3 dose every month between November 2014 and April 2015. Serum 25OHD, calcemia and calciuria were measured just before the first dose (Month 0), just before the 4th dose (M4), and one month after the 6th dose (M7). RESULTS: At M0, 25OHD was 17.5+/-9.5ng/mL. Sixty subjects (61.2%) had a 25OHD<20ng/mL and 25 (25.5%) had a 25OHD<10ng/mL. 25OHD increased significantly at M4 (35.3+/-8.0ng/mL) and M7 (40.1+/-8.5) without change in calcemia and calciuria. At M4, 2 subjects had a 25OHD slightly below 20ng/mL (17.6 and 19.7ng/mL), and none had a concentration>60ng/mL. At M7, all had a serum 25OHD>20ng/mL and 2 subjects had a value slightly above 60ng/mL (62.1 and 63.2ng/mL). CONCLUSION: A monthly supplementation with 80,000 IU vitamin D3 between November and April corrected vitamin D insufficiency in subjects in whom it was initially very frequent, without overdosing. This protocol is simple, safe and costless, and can be easily implemented when physicians detect risk factors for hypovitaminosis D in patients for whom a 25OHD measurement is not indicated. [less ▲]

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See detailHypercalcemie par mutation inactivatrice du CYP24A1. Etude d'un cas et revue de la litterature.
Seidowsky, Alexandre; Villain, Cedric; Vilaine, Eve et al

in Néphrologie & Thérapeutique (2017)

We present the case of a family whose members have high levels of serum calcium (hypercalcaemia) by loss of function of the enzyme vitamin D 24-hydroxylase due to bi-allelic mutations in the CYP24A1 gene ... [more ▼]

We present the case of a family whose members have high levels of serum calcium (hypercalcaemia) by loss of function of the enzyme vitamin D 24-hydroxylase due to bi-allelic mutations in the CYP24A1 gene: c.443 T>C (p.Leu148Pro) and c.1187 G>A (p.Arg396Gln). 24-VITD hydroxylase is a key player in regulating the circulating calcitriol, its tissue concentration and its biological effects. Transmission is recessive. The estimated prevalence of stones in the affected subjects is estimated between 10 and 15%. The loss of peripheral catabolism of vitamin D metabolites in patients with an inactivating mutation of CYP24A1 is responsible for persistent high levels of 1,25-dihydroxyvitamin D especially after sun exposure and a charge of native vitamin D. Although there are currently no recommendations (French review) on this subject, this disease should be suspected in association with recurrent calcium stones with nephrocalcinosis, and a calcitriol-dependent hypercalcaemia with adapted low parathyroid hormone levels. Resistance to corticosteroid therapy distinguishes it from other calcitriol-dependent hypercalcemia. A ratio of 25-hydroxyvitamin D/24.25 hydroxyvitamin D>50, is in favor of hypercalcemia with vitamin D deficiency 24-hydroxylase. Genetic analysis of CYP24A1 should be performed at the second step. The current therapeutic management includes the restriction native vitamin D supplementation and the limitation of sun exposure. Biological monitoring will be based on serum calcium control and modulation of parathyroid hormone concentrations. [less ▲]

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See detailPerspective and priorities for improvement of parathyroid hormone (PTH) measurement - A view from the IFCC Working Group for PTH.
Sturgeon, Catharine M.; Sprague, Stuart; Almond, Alison et al

in Clinica Chimica Acta (2017), 467

Parathyroid hormone (PTH) measurement in serum or plasma is a necessary tool for the exploration of calcium/phosphate disorders, and is widely used as a surrogate marker to assess skeletal and mineral ... [more ▼]

Parathyroid hormone (PTH) measurement in serum or plasma is a necessary tool for the exploration of calcium/phosphate disorders, and is widely used as a surrogate marker to assess skeletal and mineral disorders associated with chronic kidney disease (CKD), referred to as CKD-bone mineral disorders (CKD-MBD). CKD currently affects >10% of the adult population in the United States and represents a major health issue worldwide. Disturbances in mineral metabolism and fractures in CKD patients are associated with increased morbidity and mortality. Appropriate identification and management of CKD-MBD is therefore critical to improving clinical outcome. Recent increases in understanding of the complex pathophysiology of CKD, which involves calcium, phosphate and magnesium balance, and is also influenced by vitamin D status and fibroblast growth factor (FGF)-23 production, should facilitate such improvement. Development of evidence-based recommendations about how best to use PTH is limited by considerable method-related variation in results, of up to 5-fold, as well as by lack of clarity about which PTH metabolites these methods recognise. This makes it difficult to compare PTH results from different studies and to develop common reference intervals and/or decision levels for treatment. The implications of these method-related differences for current clinical practice are reviewed here. Work being undertaken by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) to improve the comparability of PTH measurements worldwide is also described. [less ▲]

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See detailAnalytical and clinical validation of the new Abbot Architect 25(OH)D assay: fit for purpose?
Cavalier, Etienne ULg; LUKAS, Pierre ULg; BEKAERT, Anne-Catherine ULg et al

in Clinical Chemistry & Laboratory Medicine (2017), 55(3), 378-384

BACKGROUND: We provide a clinical and analytical evaluation of the reformulated version of the Abbott Architect 25-hydroxyvitamin D assay. We compared this assay with three commercial automated ... [more ▼]

BACKGROUND: We provide a clinical and analytical evaluation of the reformulated version of the Abbott Architect 25-hydroxyvitamin D assay. We compared this assay with three commercial automated immunoassays and against a VDSP-traceable liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in six different populations. We also supplemented 40 healthy volunteers with either 600,000 IU of vitamin D2 or 100,000 of vitamin D3 to evaluate the performance of the immunoassays vs. the LC-MS/MS. METHODS: Precision and limit of quantification were assessed, 25(OH)D2 and C3-epimer recovery were calculated. Two hundred and forty samples obtained in healthy Caucasians and Africans, osteoporotic, hemodialyzed and intensive care patients and 3rd trimester pregnant women were analyzed by all methods. Correlation was studied using Passing-Bablok and Bland-Altman analysis. Concordance correlation coefficient (CCC) was calculated to evaluate agreement between immunoassays and LC-MS/MS. We verified if patients were homogeneously classified with the immunoassays when they took vitamin D2 or vitamin D3 after 1, 7 and 28 days. RESULTS: We observed excellent analytical features and showed a very good correlation to the LC-MS/MS results in the overall population. Compared to the other immunoassays, concordance of the new Abbott assay with the LC-MS/MS was at least similar, and often better in diseased populations. Althought the cross-reactivity with 25(OH)D2 was not of 100%, there was no significant difference in the classifications of the patients, either supplemented with D2 or D3 or after 7 or 28 days. CONCLUSIONS: This modified version of the Abbott Architect assay is clearly improved compared to the previous one and presents a better agreement with the LC-MS/MS. [less ▲]

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See detailA Randomised, Cross-Over Study to Estimate the Influence of Food on the 25-Hydroxyvitamin D(3) Serum Level after Vitamin D(3) Supplementation.
Cavalier, Etienne ULg; Jandrain, Bernard; Coffiner, Monte et al

in Nutrients (2016), 8(5),

Vitamin D(3) is known to be liposoluble and its release could be a factor limiting the rate of absorption. It was presumed that the presence of fat could favor absorption of vitamin D(3). However, as ... [more ▼]

Vitamin D(3) is known to be liposoluble and its release could be a factor limiting the rate of absorption. It was presumed that the presence of fat could favor absorption of vitamin D(3). However, as bioavailability is related not only to the active molecules but also to the formulations and excipients used, the optimization of the pharmaceutical form of vitamin D(3) is also important. The objective of this study was to evaluate if there is a food effect on absorption when a high dose of vitamin D(3) is completely solubilized in an oily solution. In the present cross-over study, 88 subjects were randomized and received a single dose of 50,000 IU of vitamin D(3) in fasting state or with a standardized high-fat breakfast. Assessment of serum concentrations of 25 hydroxyvitamin D(3) (25(OH)D(3)) was performed three, five, seven, 14, 30 and 60 days after supplementation. In fed and fast conditions, the 25(OH)D(3) serum concentrations were significantly higher than the baseline value three days after administration and remained significantly higher during the first month. No significant difference between fasting vs. fed conditions was observed. It is therefore concluded that the vitamin D(3) absorption from an oily solution was not influenced by the presence or absence of a meal. [less ▲]

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See detailFibroblast growth factor 23 in acute burn patients: Novel insights from an intact-form assay.
ROUSSEAU, Anne-Françoise ULg; SOUBERBIELLE, Jean-Claude; DELANAYE, Pierre ULg et al

in Burns : Journal of the International Society for Burn Injuries (2016)

INTRODUCTION: Fibroblast growth factor 23 (FGF23) is a key regulator in phosphate and vitamin D metabolism When measured with c-terminal assay, it has been shown to be increased following burn. Progress ... [more ▼]

INTRODUCTION: Fibroblast growth factor 23 (FGF23) is a key regulator in phosphate and vitamin D metabolism When measured with c-terminal assay, it has been shown to be increased following burn. Progress in understanding FGF23 physiology has emphasized the importance of assessing the intact form of FGF23. METHODS: The present cohort study is a complementary analysis of a previously published work. Patients >18 years, admitted within 24h after injury with burn surface area (BSA) >10% were included. C-terminal (c-term) and intact (i) FGF23 assay were performed at admission and every week during 4 weeks of follow-up. Inflammation and iron status were assessed at the same time points. RESULTS: Twenty patients were initially included and 12 were followed until day 28. The c-term FGF23 tended to gradually increase during the 4 weeks of follow-up while iFGF23 was quite stable into normal ranges. Iron status showed a typical inflammatory profile. C-term FGF23 was significantly positively correlated with c-reactive protein (CRP) and negatively correlated with iron levels. iFGF23 was not correlated with CRP or iron. CONCLUSION: FGF23 status following burn is characterized by a dissociation between c-term FGF23 and iFGF23. The hypothesis of an increased cleavage may be raised. Respective role of inflammation and iron levels in such deregulation need to be specified. Both c-term and intact assays should be performed in further studies aiming to increase knowledge on FGF23 regulation and effects in burn patients. [less ▲]

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See detailConsiderations in parathyroid hormone testing.
Cavalier, Etienne ULg; Plebani, Mario; DELANAYE, Pierre ULg et al

in Clinical Chemistry & Laboratory Medicine (2015), 53(12), 1913-9

Parathyroid hormone (PTH) is a major player in phosphocalcic metabolism and its measurement is very important for the correct diagnosis and treatment of several diseases. PTH determination represents the ... [more ▼]

Parathyroid hormone (PTH) is a major player in phosphocalcic metabolism and its measurement is very important for the correct diagnosis and treatment of several diseases. PTH determination represents the paradigm of quality in laboratory medicine as many variables in the pre-, intra-, and post-analytical phases strongly affect the value of the clinical information. Analytical determination of PTH has been rendered difficult by the presence, in the circulation, of truncated fragments that can cross-react with the antibodies used for its determination. In addition, pre-analytical phase is complicated by the lack of stability of the peptide and the best sample to use for its determination remains controversial, as well as sample handling and storage. PTH secretion is also affected by circadian and seasonal rhythms and by physical exercise. Finally, from the post-analytical perspective, establishment of reliable reference ranges requires further efforts as the selection criteria for reference subjects should take into consideration new variables such as gender, race and vitamin D levels. Finally, clinical guidelines have recently revised and improved the criteria for a correct interpretation of PTH values. [less ▲]

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See detailMeasurement of circulating 25-hydroxyvitamin D: A historical review
Delvin, Edgar; LE GOFF, Caroline ULg; CAVALIER, Etienne ULg et al

in Practical Laboratory Medicine (2015)

The constantly increasing requests for the measurement of serum 25-hydroxyvitamin D over the last years has led reagent manufacturers to market different automated and semi-automated methods, that being ... [more ▼]

The constantly increasing requests for the measurement of serum 25-hydroxyvitamin D over the last years has led reagent manufacturers to market different automated and semi-automated methods, that being unfortunately not fully harmonized, yield different results. Liquid chromatography coupled to tandem mass spectrometry (LC/MS2) has more recently been introduced. This approach allows the distinction between the two forms of 25-hydroxyvitamin D and to measure other metabolites. This approach also requires harmonization to curtail the differences between the different analytical methods. To meet this requirement, the American National Institutes of Health (NIH), the CDC (Centre for Disease Control and Prevention) in Atlanta, the NIST (National Institute of Standards and Technology) and the vitamin D Reference laboratory of Ghent University have pooled their expertise to develop a standardization program. This article reviews the main elements and the difficulties of the automated and semi-automated methods for 25-hydroxyvitamin D, from sample preparation to the analytical phase, as well as those related to mass spectrometry. It also addresses the issues related to the clinical decision thresholds and the possibility of measurements in different biological liquids. [less ▲]

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See detailLa sclérostine: un nouveau biomarqueur d'intérêt en néprhologie
Pelletier; Jean, Guillaume; Fouque, Denis et al

in Annales de Biologie Clinique (2015), 73(3), 305-13

Sclerostin is an osteocyte-specific glycoprotein secreted by the osteocyte and involved in the regulation of bone mass. High sclerostin levels are associated with osteoporosis, whereas low sclerostin ... [more ▼]

Sclerostin is an osteocyte-specific glycoprotein secreted by the osteocyte and involved in the regulation of bone mass. High sclerostin levels are associated with osteoporosis, whereas low sclerostin levels are correlated with higher bone mineral density. It seems interesting to investigate a potential association between sclerostin levels and vascular calcifications since sclerostin is considered as a potent inhibitor of bone formation. In chronic kidney disease, serum sclerostin levels rise as renal function declines. Preliminary studies show a positive association between serum sclerostin and vascular calcification, but the link between sclerostin and survival of patients remains unclear in the absence of large-scale studies. [less ▲]

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See detailProblems with the PTH assays
CAVALIER, Etienne ULg; DELANAYE, Pierre ULg; Nyssen, Laurent ULg et al

in Annales d'Endocrinologie (2015), 76(2), 128-133

Even if the first assay for parathyroid hormone (PTH) was published in the early 1960s, its determination remains a challenge even today. Indeed, in the circulation, PTH is present in its active form (PTH ... [more ▼]

Even if the first assay for parathyroid hormone (PTH) was published in the early 1960s, its determination remains a challenge even today. Indeed, in the circulation, PTH is present in its active form (PTH 1-84), but many PTH fragments can also be present. These fragments accumulate when renal function declines and are recognized, at different extents, by the 2nd generation ("intact") PTH assays that are widely used in the clinical laboratories. Some assays, called "3rd generation PTH" do not recognize these fragments, but are not available everywhere. Hence, different problems are also linked with PTH determination. Among them, one can cite the lack of a reference method, the lack of standardization of the assays and, sometimes, the lack of consistent reference range. We can also point out stability problems and a large intra-individual variation. A workgroup is working on these problems under the auspices of the IFCC and we hope that some of these problems will be resolved in the next years. In this article, we will discuss all the possible issues of PTH determination. [less ▲]

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See detailHow to manage an isolated elevated PTH?
Souberbielle, Jean-Claude; CAVALIER, Etienne ULg; Cormier, Catherine

in Annales d'Endocrinologie (2015), 76(2), 134-141

The aim of this article is to discuss the diagnostic approach of an increased serum PTH concentration in a normocalcemic, normophosphatemicpatient. Detection of this biological presentation is frequent in ... [more ▼]

The aim of this article is to discuss the diagnostic approach of an increased serum PTH concentration in a normocalcemic, normophosphatemicpatient. Detection of this biological presentation is frequent in routine practice all the more that PTH reference values established in vitamin Dreplete subjects with a normal renal function are used by the clinical laboratories. The first step in this diagnostic approach will be to rule out acause of secondary hyperparathyroidism (SHPT). Among these, the most frequent are vitamin D deficiency, very low calcium intake, impairedrenal function, malabsorptions, drugs interfering with calcium/bone metabolism, such as lithium salts and antiresorptive osteoporosis therapies,hypercalciuria due to a renal calcium leak. If no cause of SHPT are evidenced, the diagnosis of normocalcemic primary hyperparathyroidism(PHPT) should be considered. A calcium load test is a very useful tool for this diagnosis if it shows that serum PTH is not sufficiently decreasedwhen calcemia rises frankly above the upper normal limit. In a normocalcemic patient with hypercalciuria and a high serum PTH concentration,a thiazide challenge test may help to differentiate SHPT due to a renal calcium leak from normocalcemic PHPT. Beyond the discussion of thisdiagnostic [less ▲]

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See detailPlace de la vitamine D native en dialyse
DELANAYE, Pierre ULg; BOUQUEGNEAU, Antoine ULg; KRZESINSKI, Jean-Marie ULg et al

in Néphrologie & Thérapeutique (2015), 11(1), 5-15

Chronic kidney disease is frequent and usually responsible of mineral and bone disorder. These abnormalities lead to increased morbidity and mortality. To become active, native vitamin D needs a first ... [more ▼]

Chronic kidney disease is frequent and usually responsible of mineral and bone disorder. These abnormalities lead to increased morbidity and mortality. To become active, native vitamin D needs a first hydroxylation in the liver, and a second one in the kidney. Next to its action on bone metabolism, vitamin D also possesses pleiotropic actions on cardiovascular, immune and neurological systems as well as antineoplastic activities. End-stage renal disease (ESRD) is also associated with a decrease in vitamin D activity by mechanisms including the increase of plasma phosphate concentration, secretion of FGF- 23 and decrease in 1a-hydroxylase activity. The prevalence of 25 hydroxy-vitamin D deficiency depends on the chosen cut-off value to define this lack. Currently it is well established that a patient has to be substituted when 25 hydroxy-vitamin D level is under 30 ng/mL. The use and monitoring of 1.25 hydroxy-vitamin D is still not recommended in routine practice. The goals of vitamin D treatment in case of ESRD are to substitute the deficiency and to prevent or treat hyperparathyroidism. Interest of native vitamin D in first intention is now well demonstrated. This review article describes the vitamin D metabolism and physiology and also the treatment for vitamin D deficiency in ESRD population. [less ▲]

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See detailLe dosage de la vitamine D: considérations pré-analytiques et analytiques
LE GOFF, Caroline ULg; Souberbielle, Jean-Claude; Delvin, Edgard et al

in Annales de Biologie Clinique (2015), 73(1), 79-92

The constantly increasing requests for the measurement of serum 25-hydroxyvitamin D over the last years has led reagent manufacturers to market different automated and semi-automated methods, that being ... [more ▼]

The constantly increasing requests for the measurement of serum 25-hydroxyvitamin D over the last years has led reagent manufacturers to market different automated and semi-automated methods, that being unfortunately not fully harmonized, yield different results. Liquid chromatography coupled to tandem mass spectrometry has more recently been introduced. This approach allows the distinction between the two forms of 25-hydroxyvitamin D and to measure other metabolites. This approach also requires harmonization to curtail the differences between the different analytical methods. To meet this requirement, the American national institutes of health (NIH), the CDC (Center for disease control and prevention) in Atlanta, the NIST (National institute of standards and technology) and the vitamin D Reference laboratory of Ghent University have pooled their expertise to develop a standardization program. This article reviews the main elements and the difficulties of the automated and semi-automated methods for 25-hydroxyvitamin D, from sample preparation to the analytical phase, as well as those related to mass spectrometry. It also addresses the issues related to the clinical decision thresholds and the possibility of measurements in different biological liquids. [less ▲]

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See detailInter-method variability in bone alkaline phosphatase measurement : clinical impact on the management of dialysis patients
CAVALIER, Etienne ULg; Souberbielle, Jean-Claude; GADISSEUR, Romy ULg et al

in Clinical Biochemistry (2014), 47(13-14), 1227-30

BACKGROUND: Bone-specific alkaline phosphatase (BAP) is now recommended to assess bone turnover in hemodialysis (HD) patients. However, little is known about potential variability between methods ... [more ▼]

BACKGROUND: Bone-specific alkaline phosphatase (BAP) is now recommended to assess bone turnover in hemodialysis (HD) patients. However, little is known about potential variability between methods available to measure BAP. METHODS: We measured BAP in 76 HD patients with six different assays (Beckman-Coulter Ostase IRMA, Beckman-Coulter Ostase Access, IDS iSYS Ostase, IDS Ostase enzyme immunoassay, DiaSorin Liaison Ostase and Quidel MicroVue BAP). RESULTS: We observed a high correlation between all the assays ranging from 0.9948 (IDS iSYS vs. IDS EIA) to 0.9215 (DiaSorin Liaison vs. Quidel MicroVue). However, using the regression equations, the equivalent concentration of a Beckman-Coulter Access value of 10μg/L can range from 7.7 to 14.4μg/L and of 20μg/L can range from 16.9 to 27.9μg/L with other assays. According to Beckman-Coulter Access, 13%, 50% and 37% of the patients presented BAP values ≤10, between 10 and 20 and ≥20μg/L, respectively. Discrepancies are observed when other assays are used (concordance from 10 to 100%). CONCLUSIONS: Analytical problems leading to inter-method variation should be overcome to improve the usefulness of this marker in clinical practice. According to correlation results, recalibration of BAP assays is necessary but should not be a major issue. [less ▲]

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See detailStandardization of DiaSorin and Roche automated third generation PTH assays with an international standard: impact on clinical populations
CAVALIER, Etienne ULg; DELANAYE, Pierre ULg; LUKAS, Pierre ULg et al

in Clinical Chemistry & Laboratory Medicine (2014), 52(8), 1137-41

Background: Standardization of parathyroid hormone (PTH) assays is a major issue, especially in hemodialyzed (HD) patients. Two automated third generation PTH assays (Roche Elecsys and DiaSorin Liaison ... [more ▼]

Background: Standardization of parathyroid hormone (PTH) assays is a major issue, especially in hemodialyzed (HD) patients. Two automated third generation PTH assays (Roche Elecsys and DiaSorin Liaison) are now available. These assays are specific for the (1-84) PTH and do not cross-react with the (7-84) fragment, contrary to second generation (intact) assays. We aimed to calibrate the two methods against the WHO International PTH Standard (IS) 95/646 to see if the two assays could provide comparable results in a population of healthy subjects, HD patients and patients suffering from primary hyperparathyroidism (PHP). Methods: We selected 79 healthy subjects and two populations of patients presenting PTH disorders: 56 HD and 27 PHP patients. We reconstituted the IS in a pool of human serum containing undetectable levels of 1-84 PTH and prepared 13 serum standards ranging from 0 to 2000 pg/mL. The standards were run on the two instruments to calibrate the assays on the IS. The different populations were run before and after restandardization. Results: As these kits were differently calibrated, the results obtained after restandarization were significantly different. Restandardization process improved concordance between assays and, taking the analytical variability of the two kits into account, the results could be considered to be similar. Conclusions: Restandardization of automated third generation PTH assays with the WHO 1-84 PTH Standard significantly reduces inter-method variability. Reference ranges and raw values are totally transposable from one method to the other in healthy subjects, but also in diseased patients, e.g., with HD or those suffering from PHP. [less ▲]

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See detailEvaluation of circulating irisin levels in healthy young individuals after a single 100,000 IU vitamin D dose
CAVALIER, Etienne ULg; Mismetti, Valentine; Souberbielle, Jean-Claude

in Annales d'Endocrinologie (2014), 73(3), 162-164

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See detailCan we use circulating biomarkers to monitor bone turnover in CKD haemodialysis patients? Hypotheses and facts
DELANAYE, Pierre ULg; Souberbielle, Jean-Claude; Lafage-Proust, Marie-Hélène et al

in Nephrology Dialysis Transplantation (2014), 29(5), 997-1004

Assessing bone turnover is a key diagnostic tool in the global management of chronic kidney disease-mineral and bone disorder (CKD-MBD). Since bone biopsy is invasive and cannot be repeated in clinical ... [more ▼]

Assessing bone turnover is a key diagnostic tool in the global management of chronic kidney disease-mineral and bone disorder (CKD-MBD). Since bone biopsy is invasive and cannot be repeated in clinical practice and because bone histomorphometry is less available due to the lack of specialized laboratories, we will focus on potential biomarkers used to assess and monitor bone turnover. After briefly reviewing the pathophysiology of bone turnover in CKD and haemodialysis patients, we will focus on the strengths and limitations of the now recommended biomarkers, i.e. parathormone and bone-specific alkaline phosphatase. We will consider the clinical and also the biological aspects of the topic and also insist on the use of these biomarkers for the monitoring, and the follow-up of the turnover in haemodialysis subjects. Finally, we will discuss some of the most promising, but still not recommended, emerging biomarkers. [less ▲]

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See detailVitamin D status of schoolchildren in Northern Algeria, seasonal variations and determinants of vitamin D deficiency
Djennane, M; Lebbah, S; Roux, C et al

in Osteoporosis International (2014), 25(5), 1493-502

Summary There are no published data on the vitamin D status of children living in North Africa. In 435 healthy Algerian children 5–15 years old, we found that vitamin D insufficiency (serum 25 ... [more ▼]

Summary There are no published data on the vitamin D status of children living in North Africa. In 435 healthy Algerian children 5–15 years old, we found that vitamin D insufficiency (serum 25-hydroxyvitamin D (25OHD) <50 nmol/L) was frequent, especially in winter. Low vitamin D status was associated with increased parathyroid hormone (PTH) and leg deformation Introduction As there are no published data on the vitamin D status of children living in North Africa, we evaluated the 25OHD concentration of healthy Algerian children at the end of summer and at the end of winter. As secondary objectives, we studied the various determinants of vitamin D status and the PTH-25OHD relationship in these subjects. Methods Four hundred thirty-five children 5–15 years old were examined and had a blood sample in September 2010. Of them, 408 were sampled again in March 2011. Results Median 25OHD concentration in the whole group was 71.4 nmol/L in September and 52.9 nmol/L in March. In September, 58.4, 29.9, and 8.1 % had a 25OHD concentration below 75, 50, and 30 nmol/L respectively. In March, these percentages increased to 65.2, 41.4, and 17.4 % for the 75, 50, and 30 nmol/L threshold, respectively. In multivariate analysis, older age, darker skin phototype, low daily vitamin D and calcium intake, poor socioeconomic status, and short daily sun exposure remained significantly associated with a 25OHD <50 nmol/L at both visits. In 72 (16.6 %) children, genu varum/valgum was present. Compared to the 363 children without leg deformation, they presented more frequently with the risk factors of vitamin D insufficiency. They also had lower 25OHD concentrations and higher PTH and tALP. Serum PTH and 25OHD concentrations were negatively and significantly correlated (r=−0.43; p<0.001) without a 25OHD threshold above which PTH does not decrease anymore. Conclusion Despite a sunny environment, vitamin D insufficiency is frequent in healthy Algerian children. [less ▲]

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